That's for a Raspberry Pi 4, which should have a pretty drastic performance difference from the Raspberry Pi 3 mentioned in the article since only one of those has proper gigabit Ethernet.

It does seem pretty good though. I'm having trouble getting past 25 Mb/s in, 100 Mb/s out on my Edgerouter X.

Sure but that article was about using it on a LTE connection and the GP was asking about Pi in general. In the articles setup it's going to be bottlenecked on the cellular network anyway.

(The Pi 3 also is 4 years old now and you wouldn't want to buy it today)

Rpi 3b has proper gigabit Ethernet though.

Edit: 3B+. My bad.

"faster (300 mbps) Ethernet"[1]

[1]: https://www.adafruit.com/product/3775

It's basically a 1 Gbps PHY connected to 480 Mbps USB 2.0, so it's 240 Mbps Ethernet.

It doesn't.

Edit: It doesn't.

The 3B+ does though, IIRC (w/ PoE support too)

It doesn't. The ethernet is connected to a USB 2.0 bus. Yes the link trains at 1 gbps, but it's limited by the slow bus.